Method and die for fixing a functional element to a part made of sheet metal

ABSTRACT

Method for the attachment of a functional element having a head end and optionally a shaft part, in particular a fastener element, to a sheet metal part, optionally in liquid-tight and/or gas-tight form, wherein the functional element is pressed against the sheet metal part supported by a die button having a shaping space and sheet metal material is pressed by means of at least one movably mounted shaped part, and preferably by means of at least two such shaped parts of the die button, and by a radially inwardly directed movement of the or each shaped part, into an undercut of the functional element, with the or each shaped part forming a respective wall region of the shaping space, wherein the or each shaped part is initially radially supported by an envelope surface region of an abutment envelope and is prevented from a radially inwardly directed movement so long until the sheet metal material is drawn by the head end of the functional element into the shaping space for the formation of a pronounced recess at least largely surrounding the head end and is only then released by an axial movement of the envelope surface region of the abutment element past the or each shaped part for the radial movement for the pressing of the sheet metal material into the undercut.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority from PCT/EP03/07348 filed on Jul. 8,2003 and is a continuation-in-pan of U.S. patent application Ser. No.10/643,126 filed Aug. 18, 2003 now U.S. Pat. No. 7,160,072.

The present invention relates to a method for the attachment of afunctional element having a head end and optionally a shaft part, inparticular a fastener element, to a sheet metal part, optionally inliquid-tight and/or gas-tight form, wherein the functional element ispressed against the sheet metal part supported by a die button having ashaping space and sheet metal material is pressed by means of at leastone movably mounted shaped part, and preferably by means of at least twosuch shaped parts of the die button and by a radially inwardly directedmovement of the or each shaped part, into an undercut of the functionalelement, with the or each shaped part forming a respective wall regionof the shaping space. Furthermore, the invention relates to a diebutton, in particular for use in such a method for the attachment of afunctional element having a head end and optionally a shaft part, inparticular a fastener element, to a sheet metal part, optionally inliquid-tight and/or gas-tight form, wherein the die button has a diebutton body with at least one shaped part movably mounted therein,preferably at least two such shaped parts and also a biased abutmentelement for the or each shaped part at the centre of the die button bodyand wherein the or each shaped part forms a wall region of a shapingspace which is provided in the die button in the region of its end faceconfronting the sheet metal part and is guided by a respective obliquelypositioned guide track for a radially inwardly directed movement, whichleads to the sheet metal material being pressed into a feature of shape,i.e. into an undercut of the functional element.

A method and a die button of this kind is known from European patentapplication 99 120 559.2. There a method of this kind and a die buttonof this kind are used in order to attach different functional elementsto a sheet metal part. For example, the functional element can be anelement in accordance with FIGS. 1 a and 1 b there, where the head parthas a larger diameter than the shaft part and an undercut is formedbetween the head part and shaft part. Furthermore, the functionalelement can be an element which presents itself, in accordance with FIG.5 there, as a threaded pin with at least substantially constantdiameter. In this connection features providing security againstrotation can be provided in the region of the head end of the threadedpin. Alternatively to this, the functional element can be an element inaccordance with the German patent application 10118973.7. Furthermorethe functional element can be an element which presents itself as ahollow tube element or is formed in accordance with the European patentapplication EP 02012625.6. Furthermore, the functional element cansimply represent a nut element, with the nut body so to say forming thehead part of the element.

Important with respect to the shape of the functional element is thatone or more undercuts or features of shapes such as recesses exist inthe region of the head part or of the part of the element, which issurrounded by the sheet metal part, which are present for a form-fittedengagement with the sheet metal material in the region of a recess ofthe sheet metal part which forms an attachment of the functional elementto the sheet metal part. It is not necessary that the functional elementis equipped with a thread. The functional element can,straightforwardly, be an element which is, for example, formed as aguide pin or has a spherical head or is equipped with special featuresin order to carry out specific functions. As a further example, one canname here a pin which serves in a car to receive a spring clamp for theattachment of a carpet or a brake-line clip or a cable clip.

Furthermore, the functional element can be a hollow body element such asa nut element with our without an internal thread, which itselfrepresents the head part and does not necessarily have a shaft part. Theundercut will then, for example, be realized at the transition from theside wall of the element into its exposed end face or by thistransition.

It is known to attach functional elements by various methods and usingdifferent die buttons to sheet metal parts on an industrial scale. Thisfrequently takes place at the same time as the deformation of the sheetmetal part to form a three-dimensional article. It is problematic in allsuch methods and die buttons that they have to operate reliably overlong series.

One problem in the manufacture of sheet metal parts which have a recessin which the head part or a functional element is received inform-fitted manner lies in the fact that the previously known methods ordie buttons occasionally lead to a faulty formation of the recess, forexample in the sense that the recess is not symmetrically shaped.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to so further improve a method ora die button of the initially named kind that the method and the diebutton operate more reliably and undesired asymmetries or faultyformations of the sheet metal part do not arise, or at most only ariseextremely rarely.

In order to satisfy this object provision is made method-wise inaccordance with the invention that the or each shaped part (50) isprevented from a radially inwardly directed movement so long until thesheet metal material is drawn by the head end of the functional elementinto the shaping space for the formation of a pronounced recess at leastlargely surrounding the head end and is only then released for theradial movement for the pressing of the sheet metal material into theundercut.

Furthermore, a die button is provided in accordance with the inventionwhich is characterized in that the abutment element is biased in thedirection towards the sheet metal part, in that each shaped part issupported on the abutment element during the formation of a recess inthe sheet metal part, which takes place in the shaping space of the diebutton by pressure exerted onto the head end of the functional elementand is hereby prevented from the radially inwardly directed movement solong until the region of the abutment element against which each shapedpart is supported is moved by the said pressure from the head end of thefunctional element against the bias passed the shaped part and hasreleased the radial movement of the shaped part.

Since the shaped part or the shaped parts are first immovably held bycontact against the abutment element clearly defined conditions for theformation of the recess are present so that one succeeds in forming therecess in an orderly manner without faulty shapes of the recesses havingto be feared. Furthermore, the radial movements of the shaped partswhich cause the sheet metal material to be pressed into the features ofshape or into the undercut of the functional element, are sosynchronized by the selected method or by the die button designed inaccordance with the invention that a symmetrical deformation of thesheet metal material takes place in the region of the recess around thehead end of the functional element, whereby a symmetrical formation ofthe connection between the sheet metal part and the functional elementlikewise takes place, without faulty shapes of this connection having tothe feared.

Depending on how the functional element is designed the shaped parts canbe rounded in accordance with claim 2 at their surfaces confronting thesheet metal material, at the transition to the wall sections forming theshaping space and the said wall sections can press the sheet metalmaterial into features of shape in the radially outer side of the headend of the functional element. Should an undercut be present at thefunctional element, at the head part or between the head part and theshaft part, then, at their surfaces which confront the sheet metalmaterial, at the transition into the wall sections which form theshaping space, the shaped parts can have rounded, radially inwardlydirected projections which press the sheet metal material into theundercut. Here the rounded shape also serves for the more carefultreatment of the sheet metal part so that it is not perforated orpierced.

The method of the invention and the die button of the invention areparticularly simply designed when the shaped parts are prevented fromtheir radially inwardly directed movement by an abutment element of thedie button which is biased in the direction towards the sheet metal partand on which they are supported and when the abutment element is urgedrearwardly by the head end of the functional element through theinter-mediary of the sheet metal material during the formation of therecess until the support of the shaped parts on the abutment element isremoved.

Thus, with a relatively simple design of the abutment element, theabutment element of the die button is urged back during formation of therecess in the sheet metal part until the shaped parts are no longersupported on the abutment element and can move, as a result of thepressure exerted on to the end faces of the shaped parts confronting thesheet metal part, along the obliquely positioned guide tracks. Thismovement also takes place in synchronized manner because the sheet metalpart is simultaneously pressed by the plunger or the setting head ontothe end faces of all shaped parts at the same time and itself takes careof the synchronized movement of the shaped parts along the respectivelyassociated, obliquely positioned, guides. Since the shaped parts aremoved by the same amount in the axial direction under the action of thesetting head which presses against the sheet metal part they alllikewise move by the same radial amount in the radial direction becausethe guide tracks all form the same angle with the longitudinal axis ofthe die button. In the region of the shaped parts the die button isparticularly intimately brought into engagement with features providingsecurity against rotation formed at the functional element, inparticular groove-like and/or knurled-type features, whereby aparticularly secure security against rotation takes place.

It is particularly favourable when, for the shaped parts, respectiveguide tracks resembling T-grooves inclined to the longitudinal axis ofthe die button are provided in which the shaped parts, after the releaseof the radially inwardly directed movement slide under the pressure of aplunger and simultaneously carry out the above-mentioned axial andradial movement. The shaped parts can also have the shape of T-groovestones in cross-section, whereby a particularly favourable guidance ofthese shaped parts takes place.

It is particularly favourable when the shaping space of the die buttonis not only formed by the wall regions of the movably mounted shapedparts but is rather also formed by the fixedly arranged wall regions ofthe body of the die button which are each arranged between two movableshaped parts of the die button.

The fixedly arranged wall regions of the die button body are preferablyso designed in the starting state for the manufacture of the recess inthe sheet metal part that they are aligned with or fractionally set backrelative to the wall regions of the shaped parts which co-define theshaping space whereas, in the closed state of the die button, after thecompletion of the connection between the functional element and thesheet metal part, they are significantly offset relative to the wallregions of the shaped parts which co-define the shaping space.

This signifies that during the closing movement of the die button thesheet metal material is particularly intensively deformed in the regionof the shaped parts in the vicinity of the recess, but are, in contrast,if anything little deformed in the regions between the shaped parts.This alternating deformation of the sheet metal material in the regionof the recess leads to an extremely favourable security againstrotation.

The method is normally so carried out that the sheet metal part is notperforated, whereby a gas-tight and liquid-tight connection is possiblebetween the functional element and the sheet metal part. This can inparticular be of advantage, when the functional elements areincorporated into a floor pan of a vehicle or in regions where water orsalt solution can come into contact with the sheet metal part from theoutside. As a result of the sheet metal part not being perforated nopossibility exists for such a liquid to pass from the outer side of thesheet metal part to the inner side of the sheet metal part through theconnection between the functional element and the sheet metal part andcause corrosion there.

The invention is however not restricted to manufacturing connections inwhich the functional element does not penetrate the sheet metal part.Instead of this it is entirely possible to operate with a holed sheetmetal and to form the recess in the region of the hole of the sheetmetal or, on formation of an initially non-holed recess in the sheetmetal part, to pierce this with a follow-up hole punch. A constructionof this kind could for example be of advantage when the functionalelement is a nut element, or if one desires to have access to the threadfrom the side of the sheet metal part remote from the functionalelement, or wishes to create a situation in which a screw can be screwedthrough a nut element and through the sheet metal part, which could forexample be expedient if one operates with a thread forming or threadcutting screw, which simultaneously produces a thread in the sheet metalpart and hereby provides a conductive transition between the screw andthe sheet metal part, for example when the screw is a grounding bolt orother electrical connection.

Particularly preferred embodiments of the method and of the die buttoncan be found in the subordinate claims.

The invention will be explained in more detail in the following withreference to a preferred embodiment and with reference to the drawingsin which are shown:

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 a longitudinal section through a die button in accordance withthe invention which is intended for use with a setting head for theattachment of a functional element to a sheet metal part, with thesection plane of FIG. 1 being given as A-A in FIG. 2,

FIG. 2 a plan view of the die button of FIG. 1 in accordance with theplane II-II in FIG. 1,

FIGS. 3 and 4 representations which correspond to FIGS. 1 and 2 butafter a closing movement of a press, in which the setting head and thedie button are incorporated, with a recess being formed in a sheet metalpart and the formation of the recess standing shortly before itscompletion, and

FIGS. 5 and 6 further representations corresponding to FIGS. 1 and 2 and3 and 4 respectively, but at the end of the attachment process at apoint in time when the functional element is fully attached to the sheetmetal part.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first of all to the FIGS. 1 and 2 a die button 10 is shownthere which is arranged beneath a sheet metal part 12, with a functionalelement 14 above the sheet metal part being moved by a schematicallyillustrated setting head towards the sheet metal part in the directionof the arrow 18 and with the lower end face of the functional elementconsisting of head part 20 and shaft part 22 just having contacted thesheet metal part 12.

As is evident from FIG. 1 the head part 20 of the functional element 14is larger in diameter than the diameter of the shaft part 22, which inthis example is provided with a thread. Furthermore, the head part 20 ofthe functional element has a plurality of radial recesses 24 which areuniformly arranged around the periphery of the head part 20. In thisexample twelve such uniformly distributed recesses are provided whicheach have the shape of a rectangle with rounded corners in plan view.Furthermore, one can see from FIG. 1 that the head part 20 of thefunctional element 14 merges via a radial shoulder 26 into the shaftpart 22 provided here with thread. At this point it should be emphasizedthat this only represents one possible design of the functional element14. The functional element can have the most diverse forms as wasexplained in more detail above.

The setting head 16 can be any desired setting head. The setting headmust only be in a position to receive the functional element 14 and topress this in the direction towards the die button 10. In theillustration of FIG. 1 the setting head 16 presses both on the radialshoulder 26 of the functional element and also onto the free end face ofthe shaft part 22, with it being possible for a spring-loaded pin 31 tobe used here. This spring-loaded pin 31 can also be retracted in orderto permit the automatic feeding of further separated functionalelements.

The setting head can for example be designed in accordance with theEuropean patent application 96 109 214.5 in accordance with the Europeanapplication 00 947 949.4 or the corresponding divisional application 02012 625.6 or in accordance with the European patent application 00 931155.6.

Furthermore, a ring-like spring-loaded hold-down member can be providedwhich is not shown in FIG. 1 but which would be arranged in ring-likemanner around the central longitudinal axis 30 of the setting head 16,which simultaneously represents the central longitudinal axis of thefunctional element 22 and of the die button 10, and would have the taskof pressing the sheet metal part against the upper end face of the diebutton 10.

The design of the die button 10 is to be understood as follows: thereference numeral 40 points to a die button body which is formed with acentral stepped bore 42 arranged concentric to the longitudinal axis 30.Furthermore, in this example, three inclined T-groove-like guide tracks44 are milled or eroded into the die button body, with each inclinedguide track 44 coming from the upper end face 46 of the die button body40 and being directed towards a common central point 48 on the centrallongitudinal axis 30. The three guide tracks 44 shown in FIG. 2 arearranged at uniform intervals around the central longitudinal axis 30and each have the same inclination to the central longitudinal axis. Inthis example three movable shaped parts of the die button 10, which havean approximately triangular shape in side view, and which each have thecross-section of a T-groove stone perpendicular to the respective guidetrack, are displaceably mounted in the guide tracks resemblingT-grooves.

The shaped parts 50 accordingly have two shoulder regions 52 which slidein the guide tracks 44 resembling a T-groove, whereby the freedom ofmovement of the shaped parts 50 is restricted to an movement in thelongitudinal direction of the guide tracks, i.e. in the inclineddirection towards the centre point 48. At its radially inner side eachshaped part 50 has a part-cylindrical surface 54 which merges via asmall radial shoulder 56 into a likewise partly cylindrical wall section58. These wall sections 58 of the shaped parts 50, together with fixedlyarranged cylindrical sections 60 of the die button body, form a shapingspace 62. In this arrangement the fixed wall sections 60 of the diebutton 40 extend along a circular cylinder which is disposedconcentrically to the central longitudinal axis 30.

As is likewise evident from FIGS. 1 and 2 the shaped parts 50 have, inthe region of their upper end faces 66, respective radially inwardlydirected rounded projections 64 which—as will be later explained in moredetail—serve to press the sheet metal material into the recesses orundercuts 24 of the functional element 22. At this point expressionshould be given to the fact that the radially inwardly directedprojections 64 are not necessarily required. Instead of this thecylindrical wall sections 58 could merge via a radius or gently roundedportions into the end face of the respective shaped part 50, i.e.without such a radially inwardly directed projection 64. A design ofthis kind would be of advantage, when the functional element has an atleast substantially constant diameter and would, for example, berealized as a threaded pin, with the shaped parts 50 then having thetask of pressing the sheet metal material at points around the peripheryof the threaded pin or around the entire periphery of the threaded pininto the thread or into knurling which is impressed onto the thread orreplaces it.

A movably mounted abutment element 68 is likewise evident from FIG. 1which has a flange 70 with a compression coil spring 72 engaging theunderside of the flange in order to bias the abutment element 68upwardly. In this arrangement the upper side of the ring flange 70enters into contact with a ring shoulder 74 of the stepped bore 42 ofthe die button 40 and this limits the possible upwardly directedmovement of the abutment element 68. The abutment element 68 furthermorehas a centrally arranged pin 76, the upper end face 78 of which lies inthe plane of the end faces 66 of the shaped parts 50, with this planestanding perpendicular to the longitudinal axis 30. Furthermore, onenotes from FIG. 1 that the upper end face 46 of the die button body 42is set back from the end faces 66 of the shaped parts 50.

The compression coil spring 72 is supported at its end remote from theabutment element 68 on an abutment 82 which is held in the die buttonbody 40 by means of the spring ring 84.

The FIGS. 1 and 2 show the starting position of the die button 10 of thesetting head 16 directly before the start of the attachment of thefunctional element 22 to the sheet metal part. In this arrangement thedie button 10 is normally arranged in a lower tool of a press, whereasthe setting head 16 is carried by an upper tool of the press or by anintermediate plate of the press. Other arrangements are also possible.For example, the die button can be carried at the intermediate plate ofthe press or by an intermediate plate of the press. Further arrangementsare also possible. Inverse arrangements are also possible in which thedie button is attached in the upper tool of the press and the settinghead in the lower tool of the press or at the intermediate plate. Theprovision of a press for the actuation of the tools comprising thesetting head and the die button is however not compulsory. Thus, forexample, arrangements are possible in which the die button and thesetting head are carried by a robot in order to realize the requiredrelative movement between the setting head and the die button in thedirection of the longitudinal axis of the functional element, with thisrelative movement either taking place by the robot itself or by theaction of force from the outside. Other tools are also conceivable whichcould take care of the required relative movement of the setting headand the die button.

The designations top, bottom etc. which are used in the descriptionrefer to the geometrical arrangement of FIGS. 1 and 2 and are nothowever to be regarded as restrictive. With a different geometricalarrangement, for example with the die button at the top and the settinghead at the bottom the designations of the positions used should beinterpreted accordingly. Finally oblique arrangements of the die buttonsand the setting head are also entirely conceivable.

The attachment of the functional element 14 to the sheet metal part 12will now be described in more detail with reference to the further FIGS.3 to 6.

FIG. 3 shows the state after the press has partly closed, i.e. thesetting head 16 has already been moved in comparison to FIG. 1 by theamount h₁ in the direction of the arrow 18 in the direction towards thedie button 10. The press is not yet fully closed, which is evident fromthe spacing 86 between the lower side of the setting head 16 and thesheet metal part 12. During this closing movement of the press thesetting head has exerted a pressure on the functional element 22 so thatthe head part 20 of the functional element has produced a recess 87 inthe sheet metal part 12 which is located within the shaping space 62.

During this movement of the setting head the shaped parts 50 areimmovably held because they are prevented from movement along the guidetrack 22 by the contact of the cylindrical surfaces 54 against the outercylindrical surface 88 of the abutment element 68. One notes from FIG. 3that this contact of the part-cylindrical surfaces 54 against thecylindrical surface 88 is just about to be removed because the abutmentelement 68 has been urged rearwardly as a result of the pressure exertedby means of the functional element 22 via the sheet metal part 12 on thecentral pin 76 to such a degree that the ring surface 90 of the abutmentelement, which surrounds the central pin 76 and represents the upper endface of the cylindrical part 88 of the abutment element will soon cometo lie below the lower end faces 93 of the shaped parts 50.

If it is assumed that a further closing movement of the press leads tothe underside 92 of the setting head 16 pressing against the sheet metalpart 12, with the ring surface 90 of the abutment element 68 now lyingbelow the lower sides 93, then the shaped parts 50 can now move from theposition of FIG. 3 into the radial inwardly displaced positions inaccordance with FIG. 5. They are forced to do this because the force ofthe setting head acting in the arrow direction 18 bears on the sheetmetal part and thus on the upper end faces 66 of the shaped parts 50.

This force forces the shaped parts 50 to move along the inclined guidetracks, with them no longer being prevented from this movement by theabutment element 68, because the ring surface 90 lies below the endfaces 93 of the shaped parts 50. This movement continues until theposition of FIG. 5 is reached. One sees here that the recess formed inaccordance with FIG. 3 has now been pressed firmly against the head part20 of the functional element at three points by the radially inwardlydirected movement of the shaped parts which is associated with themovement along the inclined guides 44, with the radially inwardlyprojecting noses 64 of the shaped parts 50 having pressed the sheetmetal material into the oppositely disposed features of shape orundercuts of the head part of the functional element, so that a firmcontact of the sheet metal part against the head part 20 of thefunctional element 22 is present. Through the engagement of the sheetmetal material into the recesses 24 a high security against rotation andalso high resistance to press-out is produced. The connection betweenthe functional element 14 and the sheet metal part 12 is now finishedand the component assembly comprising the sheet metal parts and thefunctional element attached thereto can now be removed by opening of thepress from the latter. In this arrangement, on opening of the press, theupwardly directed force exerted by the spring 72 on the abutmentelement, which acts via the central pin 76 on the component assemblycomprising the functional element 14 and the sheet metal part, serves topush the component assembly upwardly whereby the shaped parts 50 areco-lifted, in particular, because the radially inwardly directedprojections engage into the sheet metal material. This lifting movementtakes place until the cylindrical part of the abutment element can slidebetween the shaped parts again in the region of the cylindrical surfaces54. At this point in time the die button is opened again and the shapedparts are moveable radially outwardly and upwardly to such an extentthat the component assembly can be removed and a new sheet metal partcan be introduced into the press in order to be connected to a newfunctional element.

The lifting of the component assembly 12, 14 out of the die button 10can also take place at least partly by the setting head if the latterexerts forces on the shaft part 22, such as for example in the settinghead of the European application 02 012 625.6. As a result of theform-fitted connection between the head part 20 and the sheet metal part12 these forces lift the shaped parts 50 and force them to a radiallyoutwardly directed movement, which takes place as a result of theinclined guide tracks until the component assembly is released by theshaped parts. The setting head must however then be so designed andcontrolled that it subsequently releases the shaft part and thus thecomponent assembly.

Since the stationary wall sections 60 of the die button body 40 are ofcircularly cylindrical shape no deformation of the sheet metal part ispossible in these regions which would prevent the removal of thecomponent assembly from the press. Moreover, one notes from FIGS. 5 and6 that the closing movement of the press is automatically terminatedwhen the setting head 16 has pressed the sheet metal part 12 onto theupper end faces 66 of the shaped parts 50 and onto the upper end face 46of the die button body. In this state the press is blocked and cannotclose further, or this blockage is recognized by the press control andleads to opening of the press. This firm contact also restricts themaximum radially inwardly directed movement of the shaped parts andensures that the pressing of the sheet metal part onto the functionalelement in the radial direction takes place by the desired amount. Thedelay of movement of the shaped parts 50 until the recess has formed inthe sheet metal part ensures a symmetrical formation of the sheet metalpart and the synchronized movement of the shaped parts which, as aresult of the mechanical design, then occurs when the abutment element68 has been pushed backwardly to such an extent that the shaped partscan move axially and radially, likewise ensures a clean symmetricaldeformation of the sheet metal part 12.

At this point it should be brought out that, although the preferredarrangement envisages three movable shaped parts 50 it would also beconceivable to operate with two shaped parts or indeed with only onemovable shaped part, with another number of shaped parts also being ableto be selected if required, for example four, five, six or more. Itwould also be conceivable to dispense with the stationary wall sectionsfor the bounding of part segments of the shaping space and to allow thesheet metal part to be pressed around the entire periphery of the recessby shaped parts movable in the radial direction. It is however regardedas directly advantageous that the sheet metal part in the region of therecess is pressed firmly against the functional element 14 locally,because this can take place to such an extent that the functionalelement is also deformed in these regions, in the region of the locallydeformed sheet metal parts, but is not deformed in the regions which arepreset by the stationary wall regions of the die button body. Thislikewise leads to a security against rotation and indeed even when nofeatures providing security against rotation are provided at the headpart. In other words, the movable shaped parts can then lead to a localindentation of the head part of the functional element, with the sheetmetal material being deformed into the local indentation and taking careof the required security against rotation. The inter-engaging regions ofthe functional element 14 and the sheet metal part 12 also take care inthis example of the required pullout resistance of the functionalelement.

Moreover the arrangement can be so contrived that an undercut is presentbetween the head part and the shaft part of the functional element, forexample in the region of the ring shoulder 26 with the sheet metalmaterial being able to be pressed into this undercut and a pulloutresistance being hereby achieved.

Finally one notes from a comparison of FIG. 6 with FIGS. 2 and 4 thatthe radially inwardly directed movement of the shaped parts 50 in FIG. 6has led to the stationary wall sections 60 being set back by apronounced amount relative to the part-cylindrical surfaces 58, whereasthis is not the case in FIGS. 2 and 4, because there the cylindricalsurfaces 58 of the shaped parts 50, are, if anything, aligned with thepartly cylindrical surfaces 60 of the die button body 40.

1. Method for the attachment of a functional element (14) having a head end (20) and optionally a shaft part (22) to a sheet metal part (12), optionally in liquid-tight and/or gas-tight form, wherein the functional element is pressed against the sheet metal part (12) supported by a die button having a shaping space (62) and sheet metal material is pressed by means of at least one movably mounted shaped part (50), and preferably by means of at least two such shaped parts (50) of the die button, and by a radially inwardly directed movement of the or each shaped part, into an undercut of the functional element (14), with the or each shaped part forming a respective wall region of the shaping space (62), wherein the or each shaped part (50) is initially radially supported by a surface (88) of an abutment element and is prevented from a radially inwardly directed movement so long until the sheet metal material is drawn by the head end (20) of the functional element (14) into the shaping space (62) for the formation of a pronounced recess (87) at least largely surrounding the head end and is only then released by an axial movement of the surface (88) past the or each shaped part for the radial movement for the pressing of the sheet metal material into the undercut.
 2. Method in accordance with claim 1, wherein the or each shaped part (50) is rounded at the surfaces (66) facing the sheet metal material at a transition into the wall section (58) forming the shaping space (62) and in that a wall section presses the sheet metal material into features of shape (24) at a radially outer side of the head end of the functional element.
 3. Method in accordance with claim 1, wherein the or each shaped part (50) has at its surfaces confronting the sheet metal material, at the transition into the wall section forming the shaping space, a rounded radially inwardly directed projection (64) which presses the sheet metal material into an undercut formed at the head end (20) of the element (14), or at a transition from the head end (20) of the functional element (14) into the shaft part (22).
 4. Method in accordance with claim 1, wherein the abutment element is urged back by the head end (20) of the functional element (14) through an intermediary of the sheet metal material (12) during the formation of the recess (87) until the support of the or each shaped part at the abutment element is removed.
 5. Method in accordance with claim 1, wherein after freeing of the radially inwardly directed movement the shaped parts (50) slide under pressure of a plunger on respective guide tracks (44) inclined to the longitudinal axis (30) of the die button and are thus simultaneously moved axially and radially.
 6. Method in accordance with claim 4, wherein after the attachment of the functional element (14) to the sheet metal part (12), the shaped parts (50) are moved in the axial direction by the biased abutment element (68), with a component assembly formed by the functional element and the sheet metal part, which is also axially moved by the abutment element (68) being released and the axial movement of the component assembly optionally causing a radially outwardly directed movement of the shaped parts permitted by the inclined guide tracks (44).
 7. Method in accordance with claim 1, wherein sheet metal material is brought by means of the shaped parts (50) into engagement with features of shape (24) providing security against rotation, formed on the functional element (14).
 8. Method in accordance with claim 1, wherein the sheet metal part (12) is not perforated and not pierced, at least in the region of the functional element (14) during its attachment to the sheet metal part.
 9. Method in accordance with claim 1, wherein a pre-holed sheet metal part is used and/or in that the sheet metal part is pierced during the attachment of the functional element by means of a self-piercing functional element or a preceding hole punch.
 10. Die button (10) for the attachment of a functional element having a head end (20) and optionally a shaft part (22) to a sheet metal part (12), optionally in liquid-tight and/or gas-tight form, wherein the die button (10) has a die button body (40) with at least one shaped part (50) movably mounted therein, preferably at least two such shaped parts and also an abutment element (68) biased in the direction towards the sheet metal part for the or each shaped part at the centre of the die button body wherein the or each shaped part (50) forms a wall region of a shaping space (62) which is provided in the die button in the region of its end face confronting the sheet metal part and is guided by a respective obliquely positioned guide track (44) for a radially inwardly directed movement, which leads to the sheet metal material being pressed into a feature of shape (24) and wherein each shaped part (50) is radially supported on a surface (88) of the abutment element (68) during formation of a recess (87) in the sheet metal part which takes place in the shaping space (62) of the die button by pressure exerted onto the head end (20) of the functional element (14) and is hereby prevented from the radially inwardly directed movement so long until the surface (88) of the abutment element (68) against which each shaped part (50) is supported is moved by the said pressure from the head end (20) of the functional element (14) against the bias past the shaped part and has released the radial movement of the shaped part.
 11. Die button in accordance with claim 10, wherein after the movement of the abutment element (68) past the shaped part (50), the obliquely disposed guide tracks (44) lead, as a result of the pressure on the sheet metal part, to the radially inwardly directed movement of the shaped parts with simultaneous axial movement of the same.
 12. Die button in accordance with claim 10, wherein the axial length of the surface (88) of the abutment element (68) which prevents the shaped parts (50) from the radially inwardly directed movement is so dimensioned that a recess (87) is formed by the head end of a functional element in the shaping space (62) of the sheet metal part at least largely surrounds the head end (20) before the support of the shaped parts at this surface (88) is removed by sliding this surface (88) past the shaped parts and the radial movement of the shaped parts is freed.
 13. Die button in accordance with claim 10, wherein the shaped parts (50) are rounded at their surfaces (66) confronting the sheet metal material (12) at a transition into the wall sections (58) forming the shaping space (62).
 14. Die button in accordance with claim 10, wherein the shaped parts (50) have, at their surfaces (66) confronting the sheet metal material (12) at the transition into the wall sections (58) forming the shaping space (62), radially inwardly directed projections (64) which press the sheet metal material into features of shape in the form of undercut formed at the head end (20), or at the transition of the head end (20) of the functional element (14) into the shaft part (22).
 15. Die button in accordance with claim 10, wherein for each shaped part (50) there is provided a guide track (44) resembling a T-groove inclined towards the longitudinal axis (30) of the die button in which it slides after freeing of the radially inwardly directed movement under the pressure of a plunger (16) and is thus simultaneously axially and radially moved.
 16. Die button in accordance with claim 10, wherein the shaping space (62) is also formed by fixedly arranged wall regions (60) of the die button body (40) which are each arranged between two movable shaped parts (50) of the die button.
 17. Die button in accordance with claim 16, wherein in a starting state prior to generation of the recess (87) in the sheet metal part, the fixedly arranged wall regions (60) of the die button body are aligned with or offset fractionally in front of or behind the wall regions (58) of the shaped parts (50) which co-define the shaping space (62), whereas, in a closed state of the die button, after the completion of a connection between the functional element and the sheet metal part, they are significantly set back relative to the radially inwardly advanced wall regions (58) of the shaped parts (50) which co-define the shaping space (62).
 18. Die button in accordance with claim 10, wherein a spring (72) disposed in a hollow cavity of the die button is provided for the biasing of the abutment element (68) in the axial direction towards the sheet metal part (12).
 19. Die button in accordance with claim 18, wherein the abutment element (68) has, at its end confronting the spring (72), a radial shoulder (70) which comes into contact with a shoulder (74) of the die button and hereby limits the maximum movement of the abutment element (68) towards the sheet metal part (12).
 20. Die button in accordance with claim 19, wherein the spring (72) is supported at its end remote from the abutment element (68) on an abutment (82) fixed in the die button.
 21. Die button in accordance with claim 20, wherein the spring (72) is pre-stressed between the shoulder (70) of the abutment element (68) and a shoulder of the abutment (82).
 22. Die button in accordance with claim 20, wherein the abutment (82) is held in a longitudinal bore of the die button by means of a spring ring (84).
 23. Die button in accordance with claim 10, wherein the abutment element (68) has a front pin part (76) a free end face (78) of which can be loaded by the head end (20) of a functional element (14), optionally through an intermediary of the sheet metal part, for the axial movement of the abutment element (68).
 24. Die button in accordance with claim 10, wherein end faces of the shaped parts (50) confronting the sheet metal part (12) project, up to the conclusion of the radially inwardly directed movement of the shaped parts (50), beyond the end face (46) of the die button (40).
 25. Die button in accordance with claim 24, wherein at the conclusion of the radial inwardly directed movement of the shaped parts (50) these are flush with the end face (46) of the die button body.
 26. Die button in accordance with claim 10, wherein said features providing security against rotation arc at least one of ribs and grooves. 